Thread: Electric Fans

Tweet

Hey guys...
I currently am working on my 1997 VW GTI VR6, shaving the engine bay and, hiding all the wiring, generally improving the car.
I'm about 1/4 done and I've gotten to the part where I want to improve the cooling system.

I've already pulled out all the unecessary parts and pieces(coolant reserviors/by-passes) heater core, a/c parts, power steering. The works!!!

I've already cut out my stock fans(they weigh 20 lbs) and protrude into the engine bay.
My radiator surface area measures 24.5" wide by 15" tall.

MY MAIN QUESTION:
1) What is the ground-rule CFM requirement for a 6cyl motor?
Providing the car will be run slightly warmer than daily driven operating temps(track/drags)

2) CSR's website has the best CFM/Cost ratio. When putting two 11" fans next to each other, do I add the CFM's from the two fans together to equal the total CFM across the Radiator or is there a formula???

Now, according to a few sites I've found in search of an answer to my two questions, 1600 CFM is good for a daily driven 6cyl.
But no-where can I find how to make the math work for two fans next to each other.

HELP ME GUYS!!!

ok...getting closer to a solution...

The 11" fan pulls 1000cfm(roughly)...
I'd put two CSR's superduty 12" fans that pull 2kCFM each but they are .5" to wide and will NOT fit in between the end tanks on my radiator...



Any more input would be appreciated!
Thanks!

Ford electric fans from a Lincoln Mark VIII appears to be the highest cfm fan. It is a 2 speed fan so it runs at a lower RPM & only runs on high speed when needed. As I recall it is 18" in diameter so a shroud would have to be made. The V8 Mustangs are the same except for the shrouding.

I have heard that Walker uses this fan motor with their shrouding.

CFM's ratings on after market fans will not be seen in real life conditions, so I would use the highest CFM fan that will fit.

IMHO I would try to find a fan rated around 2700 cfm.

2700 CFM is a heaty fan...keep in mind, I only have 15" of cool-able vertical surface on the radiator.

The ratings on the fans I've looked at (Flexalite, CSR, Derale) are all at 0º Static Pressure...so you're right.

I read that many radiator manufacturers recommend that 70% of the radiator surface needs to be covered by a fan.

If I have a surface that is 367.5"squared, and a 16" fan only takes up 201" of that surface(pi*r^2)thats just over 54% of the radiator being covered.
.
.
.
.
.
I may have an easier way to figure this out, but I never got this far in mech. engineering class...

Does anyone know how to find an estimated CFM rating by the pitch of a fan blade, amperage and fan diameter? I could always try to find the CFM of my stock fans and work off that...

also check out spal-usa.com ...............

I have a straight blade 16" fan from them rated around 2600 cfm and it weighs 5 lbs.

Kitz

Spal has some good stuff!!!
I checked them out and started to realize that efficiency was going to cost me $$$$

Anyways...that 16" fan you're telling me about is starting to sound like a practical solution, in addition to a smaller fan along side of it.

I have an oil cooler on the bottom left corner infront of the radiator...I could use a smaller 7.5" fan from Spal's bike fan section and mount that next to the 16" puller.

VR6's are known for running hot anyways...anything bigger than the stock 8" fans will be an improvement.

You cover 100%of the radiator core by using a shroud.

The only practical way of comparing fan cfm's is by the amps they draw. I once measured the Lincoln fan & as I recall it measured 40 amps.

The info is on this site do a search.

Thanks Don...
I'll keep an eye out for higher amperage fans...
Thank you for all the tips!!

http://streetmachinesoftablerock.com...topic.php?t=82

I read 3 of those links before I started this thread...They're more installation guides than anything...but they were helpful regardless!
The fourth I didn't read at all...but I will at work

That DCControl site is awesome...
It looks like I'll be running one of their control modules along with an aux' switch to their dual fan setup.
Thanks!!